Crystal Structure and Physical Properties of BiCoPO5

✍ Scribed by Said Nadir; J.S. Swinnea; H. Steinfink

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 164 KB
• Volume: 148
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8450

✦ Synopsis

R 1 [I' '2 (I )] ‫؍‬ 0.025, R 1 for all re6ections ‫؍‬ 0.030. Co is in a slightly distorted octahedral coordination with Co+O bonds ranging from 2.007(5) to 2.150(5) A > . Bi is in six-fold coordination to oxygen in a distorted octahedral coordination with Bi+O bonds ranging from 2.129(4) to 2.693(5) A > . The lone-pair electrons are 0.39 A > from the Bi nucleus. The PO 4 tetrahedron is quite regular with P+O bonds 1.532(5)+1.558(5) A > . Phases in the solid solution series BiNi 1؊x Co x PO 5 , 04 4x4 41 are monoclinic. Magnetic susceptibility measurements show that they are all antiferromagnets with T N varying from 20 K for the pure Ni phase to 15 K for pure Co. The materials are semiconductors with E g ‫؍‬ 0.38 ev and E g ‫؍‬ 0.9 ev for the Ni and Co compounds, respectively. When monoclinic BiCoPO 5 is heated past the melting point to 9503C it decomposes and an orthorhombic phase is formed. Single crystal Weissenberg photographs of this new phase yield lattice parameters a ‫؍‬ 14.688(3) A > , b ‫؍‬ 11.229(2) A > , c ‫؍‬ 5.438(1) A > , space group Ibam or Iba2.